Callout

Using Callouts

New property ShowLabelAsDataCallout has been added to DataLabelFormat class and IDataLabelFormat interface, which determines either specified chart’s data label will be displayed as data callout or as data label. In the example given below, we have set the Callouts.

using (Presentation presentation = new Presentation())
{
    IChart chart = presentation.Slides[0].Shapes.AddChart(ChartType.Pie, 50, 50, 500, 400);
    chart.ChartData.Series[0].Labels.DefaultDataLabelFormat.ShowValue = true;
    chart.ChartData.Series[0].Labels.DefaultDataLabelFormat.ShowLabelAsDataCallout = true;
    chart.ChartData.Series[0].Labels[2].DataLabelFormat.ShowLabelAsDataCallout = false;
    presentation.Save("DisplayChartLabels_out.pptx", SaveFormat.Pptx);
}

Set Callout for Doughnut Chart

Aspose.Slides for .NET provides support for setting series data label callout shape for a Doughnut chart. Below sample example is given. 

Presentation pres = new Presentation("testc.pptx");
ISlide slide = pres.Slides[0];
IChart chart = slide.Shapes.AddChart(ChartType.Doughnut, 10, 10, 500, 500, false);
IChartDataWorkbook workBook = chart.ChartData.ChartDataWorkbook;
chart.ChartData.Series.Clear();
chart.ChartData.Categories.Clear();
chart.HasLegend = false;
int seriesIndex = 0;
while (seriesIndex < 15)
{
	IChartSeries series = chart.ChartData.Series.Add(workBook.GetCell(0, 0, seriesIndex + 1, "SERIES " + seriesIndex), chart.Type);
	series.Explosion = 0;
	series.ParentSeriesGroup.DoughnutHoleSize = (byte)20;
	series.ParentSeriesGroup.FirstSliceAngle = 351;
	seriesIndex++;
}
int categoryIndex = 0;
while (categoryIndex < 15)
{
	chart.ChartData.Categories.Add(workBook.GetCell(0, categoryIndex + 1, 0, "CATEGORY " + categoryIndex));
	int i = 0;
	while (i < chart.ChartData.Series.Count)
	{
		IChartSeries iCS = chart.ChartData.Series[i];
		IChartDataPoint dataPoint = iCS.DataPoints.AddDataPointForDoughnutSeries(workBook.GetCell(0, categoryIndex + 1, i + 1, 1));
		dataPoint.Format.Fill.FillType = FillType.Solid;
		dataPoint.Format.Line.FillFormat.FillType = FillType.Solid;
		dataPoint.Format.Line.FillFormat.SolidFillColor.Color = Color.White;
		dataPoint.Format.Line.Width = 1;
		dataPoint.Format.Line.Style = LineStyle.Single;
		dataPoint.Format.Line.DashStyle = LineDashStyle.Solid;
		if (i == chart.ChartData.Series.Count - 1)
		{
			IDataLabel lbl = dataPoint.Label;
			lbl.TextFormat.TextBlockFormat.AutofitType = TextAutofitType.Shape;
			lbl.DataLabelFormat.TextFormat.PortionFormat.FontBold = NullableBool.True;
			lbl.DataLabelFormat.TextFormat.PortionFormat.LatinFont = new FontData("DINPro-Bold");
			lbl.DataLabelFormat.TextFormat.PortionFormat.FontHeight = 12;
			lbl.DataLabelFormat.TextFormat.PortionFormat.FillFormat.FillType = FillType.Solid;
			lbl.DataLabelFormat.TextFormat.PortionFormat.FillFormat.SolidFillColor.Color = Color.LightGray;
			lbl.DataLabelFormat.Format.Line.FillFormat.SolidFillColor.Color = Color.White;
			lbl.DataLabelFormat.ShowValue = false;
			lbl.DataLabelFormat.ShowCategoryName = true;
			lbl.DataLabelFormat.ShowSeriesName = false;
			//lbl.DataLabelFormat.ShowLabelAsDataCallout = true;
			lbl.DataLabelFormat.ShowLeaderLines = true;
			lbl.DataLabelFormat.ShowLabelAsDataCallout = false;
			chart.ValidateChartLayout();
			lbl.AsILayoutable.X = (float)lbl.AsILayoutable.X + (float)0.5;
			lbl.AsILayoutable.Y = (float)lbl.AsILayoutable.Y + (float)0.5;
		}
		i++;
	}
	categoryIndex++;
}
pres.Save("chart.pptx", Aspose.Slides.Export.SaveFormat.Pptx);

FAQ

Are callouts preserved when converting a presentation to PDF, HTML5, SVG, or images?

Yes. Callouts are part of the chart rendering, so when you export to PDF, HTML5, SVG, or raster images, they are preserved together with the slide’s formatting.

Do custom fonts work in callouts, and can their appearance be preserved on export?

Yes. Aspose.Slides supports embedding fonts into the presentation and controls font embedding during exports such as PDF, ensuring the callouts look the same across different systems.